Tremadoc-Arenig acritarchs from the Annascaul Formation, Dingle Peninsula, Co. Kerry, Ireland

The Annascaul Formation occurs in the southeast part of the Dingle Peninsula and occupies a narrow outcrop strip running from Minard Bay northeastwards to Caherconree Mountain. It comprises the oldest rocks in the peninsula and is composed of a >500 m succession of deep marine mudrocks, siltstones, turbiditic sandstones, and mud-matrix melange deposits. The formation was traditionally considered to be Silurian in age; however lithological, structural, and metamorphic evidence indicated a much older age, although, diagnostic palaeontological evidence was lacking. Preliminary palynological study in 1996 revealed the presence of Early Ordovician acritarchs in two samples from Minard Bay. In the present study, acritarchs are recorded from 15 samples from the formation at Minard Bay and from inland exposures around Annascaul. Despite high thermal maturity, the acritarchs are moderately well preserved. The majority of the taxa are well-established species; one new species, Cymatiogalea vanguestainei, is erected. Four distinctive but low-diversity acritarch assemblages are described; these indicate an age range of early Tremadoc to early-mid Arenig for the Annascaul Formation.